Software Engineer

A permutation is a mathematical technique that determines the number of possible arrangements in a set when the order of the arrangements matters. A string of length 'N' has 'N'! permutations.

Given an array of distinct integers, return all the possible permutations of the array.

Example:

'ARR[]' = [1, 2]

The size of the array is 2. So, the total number of permutations is 2! = 2. The possible permutations are [1, 2] (the array itself) and [2,1] where the position of element 1 in the original array is swapped with element 2 and vice-versa.   

Note:

1. All the numbers in the array are unique.

2. You can return the answer in any order.

3. The original array is also a permutation of the given array.

You have to implement an iterator for ‘FLATTEN_2D’ to flatten a two-dimensional array ‘ARR_2D’ into a one-dimensional array ‘ARR_1D’. The iterator should support the following two operations:

‘NEXT’: The first call to ‘NEXT’ should return the first element of ‘ARR_2D’. Each subsequent call should return the next element in the row-wise traversal of ‘ARR_2D’.

‘HAS_NEXT’: It should return ‘true’ if the iteration has more elements to traverse; otherwise, if ‘NEXT’ has traversed the entire ‘ARR_2D’, return ‘false’.

Try to code this using only iterators in C++ or iterators in Java.

The ‘FLATTEN_2D’ object will be instantiated and called as follow:
  FLATTEN_2D it = new FLATTEN_2D(ARR_2d);
  while (it.hasNext()) {
      arr1d.append(it.next());
  }

Example:

ARR_2D = [ 
          [0, 1],
          [2, 3, 4],
          [],
          [5] 
        ]
The computed ‘ARR_1D’ should be as follows:
ARR_1D = [0, 1, 2, 3, 4, 5]
So, the printed output will be: 0 1 2 3 4 5

You are given two binary trees with 'n' and 'm' nodes respectively.

You need to return true if the two trees are identical. Otherwise, return false.

Example:

For the trees given below:- 

The given trees are identical as:-
1. The number of nodes in both trees is the same. 
2. The number of edges in both trees is the same. 
3. The data for root for both the trees is the same i.e 5. 
4. The data of root -> left (root’s left child) for both the trees is the same i.e 2.
5. The data of root -> right (root’s right child) for both the trees is the same i.e 3.
6. The data of root -> right -> left ( left child of root’s right child) for both the trees is the same i.e 6.
7. Nodes with data 2 and 6 are the leaf nodes for both the binary trees. 

You are given a string 's', and a dictionary of words 'dict' containing 'n' words. Your task is to add spaces in 's' to form valid sentences, where each word is a word from the dictionary.

You need to return all possible sentences that can be formed using the given dictionary.

Note :

The same word from a dictionary can be used as many times as possible to make sentences.

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